FRACTIONS


Subtracting Fractions with Unlike Denominators

When Fractions have Unlike Denominators, the

Least Common Demonator must first be found.


2

3
-
1

5

To subtract these fractions, find the least common denominator.

The least common denominator of 3 and 5 is 15.





 2

 3

15 ÷ 3 = 5



 2    x    5    =

 3    x    5    =
10

15


2

3
=
10

15




 1

 5

15 ÷ 5 = 3



 1    x    3    =

 5    x    3    =
3

15


1

5
=
3

15





With like denominators, the fractions can now be subtracted.



2

3
-
1

5



is the same as


10

15
-
3

15
=
7

15

therefore


2

3
-
1

5
=
7

15




If the resulting proper fraction can be reduced, then do so.

5

6
-
1

3
Common Denominator = 6


5

6
-
2

6
=
3

6


3

6
=
1

2




RULE

Subtracting Fractions with Unlike Denominators
Change those Fractions to Fractions with Like Denominators.

Subtract the Numerators. Keep the Like Denominator.

If the Proper Fraction can be Reduced, then do so.